1. Field of the Invention
The present invention relates to a chamfering air tool for rounding an edge of a subject with softly moving in surface contact with the edge of the subject, and more particularly to a chamfering air tool in which a rotating cutter having a shape suitable for chamfering is mounted to a rotary shaft having an air hole, a rotational cap having a guide flange for guiding an air tool in surface contact with a subject is installed to a casing, and an air discharge hole is formed to be inclined to discharge air in a direction approximately opposite to a resultant of a force for advancing the air tool and a force for cutting the subject, whereby the guide flange and the rotating cutter shapes a chamfering portion uniformly and stably, the air blown to the air hole discharges out cut chips and dusts and cools down to improve efficiency of work, and the air tool is more closely adhered to the subject and easily advanced by means of the reaction of the air discharged to an air discharge hole, thereby making the chamfering air tool be used more conveniently.
2. Description of the Prior Art
A conventional chamfering air tool is configured so that a driving shaft for rotating by air pressure and a rotary shaft orthogonal to the driving shaft and receiving a driving force from the driving shaft are installed in a casing, and a plurality of bites are attached to an end of the rotary shaft to process an edge of a subject to be processed. In addition, in order to protect the bites and prevent crushed pieces from being scattered, a cap may be attached to the casing around the bites.
As an alternative, one rotating cutter may be installed instead of a plurality of bites. Such a rotating cutter has a plurality of chamfering blades densely protruded at regular intervals with a toothed shape so as to grind a subject to be processed.
In case of such a conventional chamfering air tool, a shape of the cutter is not coincided with the shape to be chamfered, so a worker should handle the air tool according to the shape of the chamfering portion for processing. In this work, it is not easy to apply a uniform force, and the subject is not chamfered regularly, particularly for a round, since an interface between the subject and the chamfering air tool is not regular due to wrong posture of the worker. That is to say, since a worker chamfers an edge of the subject with the use of the cutter by eye measure, a chamfering angle is not regular and much time is taken for the work, inefficiently.
In addition, in the work using the conventional cutter, the subject and the cutter may be heated due to friction between them, so a worker may get burned. Moreover, if the cutter is heated, abrasion resistance of the cutter is deteriorated, so the cutter should be exchanged very frequently. Furthermore, cut chips of the subject that is cut by the cutter are not easily discharged, thereby disturbing the cooling process or the chamfering work.
In addition, a worker should apply a uniform force to the cutter of the chamfering air tool so that the cutter keeps contacting with the subject, and the chamfering work should be conducted with advancing the cutter in a constant direction. However, a worker may not chamfer the subject with keeping a right posture since the air tool itself is heavy, the discharged air disturbs the worker, and the cut chips are often scattered to the face of the worker. That is to say, the air tool generally receives air from a compressor and rotates an air motor and a driving shaft connected the air motor by means of the air pressure, and the cutter is mounted to the rotary shaft perpendicularly mounted to the driving shaft. Thus, after generating a rotational force, the air is discharged out through a hole formed in the casing. However, wrong position and orientation of the hole causes defects in the chamfering work.
Moreover, in the conventional chamfering air tool, since a bolt hole formed for connection of steel structure cannot be filleted well, gap may be generated among a bolt head, a nut and the steel structure. In addition, since paint is not uniformly coated, rain or the like may be introduced into the gap to corrode the inside of the steel structure, thereby causing serious problems in safety.
Such problems are caused in constructing a building structure such as a bridge or a large ship in a shipyard. Such inferiorities are very serious since they may cause may take a terrible toll of lives.